1. Field of the Invention
The invention relates to maintenance interval monitors, especially those designed for use with motor vehicles.
2. Description of the Prior Art
The maintenance of a modern motor vehicle is very important because of the constantly increasing cost of a new vehicle and of any major repairs to the vehicle. Most major repairs on a motor vehicle can be eliminated or delayed by proper attention to a relatively small number of items. Properly maintaining these items extends the period between major repairs as well as extends the vehicle life. Therefore it is important that the vehicle owner be aware of the need to service these items.
Generally, the important items need maintenance at different, independent intervals. For this reason, it is difficult for the owner to keep track of which item needs maintenance at which interval.
Additionally, the maintenance intervals vary depending upon the vehicle's actual use. For example, oil must be changed frequently when the vehicle is used only for short trips, while more miles are acceptable between oil changes if the vehicle is used only for long distance, highway driving. This variability of usage further complicates the problem of vehicle maintenance, because generally manufacturer maintenance recommendations are for only a single mileage value, thereby creating many non-optimal maintenance situations. For these reasons, a number of types of maintenance interval monitors have been proposed.
For example, U.S. Pat. No. 4,031,363 involved an electronic monitor which indicated the need for vehicle maintenance after a fixed time interval or after a fixed distance interval. The distance traveled was determined from the speedometer cable or other mileage sensor. The monitor did not allow the intervals to be changed by the vehicle owner.
U.S. Pat. No. 4,159,531 related to an electronic service indication system. When queried, the system indicated the next mileage at which maintenance should be performed and the names of the tasks to be performed. The suggested mileages between tasks was not alterable by the user and there was no prompting to indicate when service was to be performed. The system also allowed storage of the actual mileages at which service was performed by the proper facility, but required special equipment to record the values.
In U.S. Pat. No. 4,307,291, a mechanical maintenance monitor with a series of rotatable wheels was driven by the vehicle's speedometer cable. An electrical circuit closed to indicate set interval completion. A number of different intervals corresponding to different tasks could be set by the manufacturer, but the maintenance intervals were not adjustable by the owner.
U.S. Pat. No. 4,404,641 disclosed an electronic equipment maintenance monitor which compared elapsed running time with owner selectable time values to enable warning indicators and equipment disabling devices.
None of these devices was totally satisfactory for motor vehicle maintenance monitoring. The monitor should be very easy to install in a vehicle. This eliminates the devices requiring elaborate electrical connections or connections to the vehicle speedometer cable. Some object to connecting other meters than the speedometer to the speedometer cable. The monitor should use miles for the service interval because mileage is the common standard used to determine maintenance requirements. This eliminates the devices which only measure elapsed time. The monitor should allow the owner to individually select or vary maintenance intervals, to allow for individual vehicle use differences. This eliminates any devices which have maintenance intervals settable only by the manufacturer.